Optical fibers, both multi-mode and single mode, are commonly used for the transmission of signals of all sorts, including communication and data signals. Communications systems often transmit signals between transceivers (i.e., devices that can both transmit and receive optical signals) via different fibers in each direction. More specifically, one or more fibers will transmit signals from the first transceiver to the second, and one or more of the other fibers will transmit signals from the second transceiver to the first. In this manner, optical signals are not traveling along the same fiber in different directions.
This arrangement would be fairly simple to organize for two transceiver devices that are permanently optically connected, but in practice transceivers are typically connected through a much larger network of optical fibers, connectors and patch panels. For example, a common optical system includes multiple transceivers at one end, 2-fiber patch cords that are connected to the transceivers and to duplex adapters mounted on a patch panel, a fan-out transition device connected to the duplex adapters that connects to a multi-strand fiber optic trunk cable (12 fibers per cable is common, and the fiber strands may be in ribbon form) via an array adapter, a second fan-out transition device connected to the opposite end of the optic trunk cable via a second array adapter, and corresponding transceivers connected via 2-fiber patch cords to the second fan-out transition device through duplex adapters. Thus, it is important to be able to track individual optical fibers in the various devices and cables between the transceivers in order to ensure that the individual transceivers are connected as desired.
To ensure intermateability of cabling components and signal polarity, standards have been created to define arrangements of fibers, cables, adapters and connectors. For example, one such standard for array connectors, TIA-604-5B, is directed to multi-fiber push-on (MPO) fiber optic connector intermateability. Another standard, TIA 568-B.3 with addendum No. 7 written by committee TR-42, is directed to maintaining optical fiber polarity with systems using array connectors and adapters, including MPOs. Systems built using these methods utilize fiber optic cables, adapters, transition devices and patch cords that are typically partially or completely unique to one of these methods.
In some instances, transceivers may utilize less than all of the fibers of the trunk cable. For example, a transceiver may have only four channels, each of which has a “transmit” fiber and a “receive” fiber. Commonly, two such transceivers would utilize the outer four fibers on either end of a 12-fiber trunk cable; i.e., the transmit fibers would use fibers 1-4 of the trunk cable, and the receive fibers would use fibers 9-12 of the trunk cable. Thus, the devices would occupy only eight of the 12 fibers of a 12-fiber trunk cable, which would result in inefficient use of the trunk cable. However, adding more transceivers onto the trunk cable in order to utilize all of the trunk cable fibers may complicate the connection scheme. One approach to this problem is proposed in co-assigned and co-pending U.S. patent application Ser. No. 12/608,230, which provides schemes and accompanying devices that enable multiple transceivers having fewer than 12 fibers to connect with proper polarity via an available 12-fiber trunk cable.
A different situation may also arise when a transceiver has more than 6 channels (12 fibers); for example, each of a pair of transceivers may have 12, 18 or even 24 channels. It may also be desirable to provide schemes and devices that enable such transceiver to utilize 12-fiber trunk cables.